Open Access

Wheat is one of the world's most important food crops. While wheat yield is severely limited by the impact of environmental stresses such as drought and heat, forecasts for the next decades indicate increases in temperature as a result of climate change. Therefore, studying wheat's adaptation to heat waves can be vital for developing wheat varieties that are better adapted to climate change. It is also important to develop methodologies to help assess genotypic variability in heat shock tolerance. The present research aims to establish a methodology to select, under field conditions, genotypes that are more heat tolerant. We used portable plastic houses to induce transient increases in air temperature at different key phenological stages (heading, anthesis and mid grain filling) together with different planting (normal versus late) times to assess different temperatures during the whole cycle. Under good agronomic conditions (fully irrigated crop, planted at the right time), the effect of transient heat stress (i.e., heat waves) on grain yield directly affected grain number per spike, particularly when stress occurred at heading; TKW was less affected and the effect did not appear to be mediated primarily by a decrease in leaf photosynthesis. The effect of transient heat on late planting was more severe, with stress occurring at heading being the one that most affected grain yield. Moreover, in the late planting, photosynthesis was severely affected by heat. Genotypic differences were detected for HI and kernel weight/spike, particularly in the late planting.

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